Entry 2 senses · 2 variants Webster, 1913 Pisiform · Pi·si·form · IPA a. n. 01 a. Resembling a pea or peas in size and shape; as, a pisiform iron ore. 1. Resembling a pea or peas in size and shape; as, a pisiform iron ore. 02 n. A small bone on the ulnar side of the carpus in man and many mammals. See Illust. of Artiodactyla. 1. A small bone on the ulnar side of the carpus in man and many mammals. See Illust. of Artiodactyla.(Anat.) See: Artiodactyla